Optical devices such as endoscopes are used to view the interior of a body, such as an internal cavity of a human body, for both diagnosis and treatment of medical conditions. Optical devices are also used to observe the interior of other bodies or objects that do not readily permit direct observation, for example, a borescope used to inspect nuclear fuel elements in nuclear reactors or rotors in turbomachinery, and similar optical devices are used to view the interior of scale-models of buildings in architectural endoscopy.
These optical devices, for example, an analog or digital camera or a video camera, are often coupled to an imaging device to visualize anatomy of the interior of the body. The images are useful in diagnosis, comparison, surgical or therapeutic procedures, medical review, training and the like. Lenses in the optical device relay an image of an object to the imaging device. Images produced by the imaging device are displayed on a monitor, for example, during surgical or therapeutic procedures. In color imaging systems, light rays of differing wavelengths incident on the lenses are refracted at different angles, resulting in chromatic aberrations.
Endoscopes designed for direct viewing and/or for viewing with video cameras are conventionally color-corrected to reduce chromatic aberrations in the spectral range from about 480 nanometers (nm) to about 644 nm.